What Is Carsickness?

Thank you IFLScience for this little gem of a fact. Well, less of a fact and more of an evolutionary hypothesis, but I have to say, it does make sense.

In terms of our evolution, we were never built for car travel. For thousands and thousands of years, our thalamus – the hub of how we process sensory information – became tuned to deal with the sensory input from walking and running. In these processes, our body feels in sync with our wider sense of speed, with our vision and other senses providing a sensory match.

But in a car or train, it’s a different story. Physically, we are sitting still, our muscles aren’t moving, and the air around us feels motionless, yet we have other sensory input that tells us there is a lot of movement going on.

“There’s a sensory mismatch there,” Dr Burnett explains. “And in evolutionary terms, the only thing that can cause a sensory mismatch like that is a neurotoxin or poison. So the brain thinks, essentially, it’s been being poisoned. When it’s been poisoned, the first thing it does is get rid of the poison, aka throwing up.”

This little snippit was taken from a much longer interview on NPR about the “Idiot brain”, i.e. the various apparently illogical ways the brain stores information. If that’s the sort of thing that would interest you, you can listen to it and/or read the transcript here. You can also buy Burnett’s new book, for that matter.


  1. Lofty says

    My wife doesn’t get motion sickness at all. It made her my ideal companion back in the 80’s when I was an amateur rally driver. As a passenger I get it fairly easily but never when I’m driving. I read somewhere that susceptibility to motion sickness was related to whether you had “steady” vision or “unsteady” vision. I can’t find any online references to this theory, sadly.

  2. enkidu says

    Hmmm. Sounds like EP bullshit to me.

    Maybe It explains that little known historical fact that the Scythians (or do I mean Seleucians) actually all fell off their horses, rather than aiming and accurately firing arrows at the gallop.

  3. inquisitiveraven says

    Enkidu, have you ever actually ridden a horse?

    You don’t sit passively on the animal’s back. Especially if you don’t have stirrups, you have to hang on with your legs. You also move in sync with the horse. If you don’t do that, you’ll throw its balance off and if you don’t fall off anyway, it’s likely that the horse will try to find a way to dump you. You’d be surprised at how creative they can be at getting rid of unwanted riders when they put their minds to it.

    Also, the other factor mentioned, not feeling the air moving, doesn’t apply to riding a horse.

    Now are there any records of people getting motion sick in enclosed animal powered carriages?

    Also, Lofty’s comment about only getting carsick when not driving has me wondering how common that is. Also, could opening the window, thereby getting the feeling of air moving help? The problem with that one is that it kills your gas mileage.

    • enkidu says

      Yes actually, not that it has any relevance. It’s a variant of the “Were you there” question.

      Perhaps you would prefer my theory of why there are no people living on islands or why the trains are overflowing with vomit.

      Motion sickness has a recognised physiological cause; unaccustomed (there I’ve emphasised the key word for you) movement of the fluid in the semicircular canals. The human brain, or at least some of them, can learn and get used to new sensations. Individuals will have different sensitivities, for sure, but almost no-one has motion sickness for ever. This is at least testable, rather than some “just so” story of the Serengeti.

      Read any of PZ’s posts on EP, he would shed this nonsense in ten seconds.

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